Field of the Invention
The present invention relates to a method and device for molding a fiber-reinforced plastic member.
Description of the Related Art
Being lightweight and excellent in mechanical strength, fiber-reinforced plastics (FRPs) are used for structural members of aircrafts, windmill blades, automobiles, marine vessels, railway cars, and the like.
The vacuum assisted resin transfer molding (VaRTM), for example, shown in Japanese Patent No. 4805375 is known as one of the methods for molding a fiber-reinforced plastic member.
The VaRTM method involves covering a fiber base material disposed on a mold with a bag film, which is a covering material, and then depressurizing the inside of the bag film to a predetermined degree of vacuum to thereby inject a resin to the inside of the bag film, and heating and curing the resin impregnating the fiber base material. The VaRTM method can mold a fiber-reinforced plastic member at a lower cost compared to the autoclave molding method, in which a pre-preg covered with a bag film is pressurized and heated and cured at the same time in an autoclave.
In the VaRTM method, a pressure plate is sometimes interposed between the bag film and the fiber base material. The pressure plate is provided to smooth the surface of the fiber-reinforced plastic member facing the bag film. When the fiber-reinforced plastic member to be molded is flat, a flat plate-like metal material can be used as the pressure plate. However, when the fiber-reinforced plastic member has, for example, an arc-shaped cross-section, the conventional practice is, as shown in FIGS. 4A and 4B, to form a molding surface 201 of a mold 200 facing a fiber-reinforced plastic member 205 into an arc shape, and also form a molding surface 203 of a pressure plate 202 facing the fiber-reinforced plastic member 205 into an arc shape.
The molding surface 203 of the pressure plate 202 is conventionally formed by cutting work of cutting a cold-rolled material, etc. Since the pressure plate 202 needs to be produced so as to have the molding surface 203 which conforms to the cross-sectional shape of the fiber-reinforced plastic member 205, it is necessary to prepare the pressure plates 202 which correspond to the respective fiber-reinforced plastic members 205 with different cross-sectional shapes. This makes the pressure plate 202 manufactured by cutting work expensive, which is a bottleneck in reducing the cost of manufacturing the fiber-reinforced plastic member 205 by the VaRTM method.
The present invention has been made on the basis of this problem, and an object thereof is to provide a method for molding a fiber-reinforced plastic member which can reduce the manufacturing cost of a fiber-reinforced plastic member by keeping down the production cost of the pressure plate.